The present invention relates to printed circuit boards in general, and more specifically to components employed in the manufacturing of printed circuit boards and other articles.
U.S. Pat. Nos. 5,153,050, 5,674,596 and 5,942,315, all to Johnston, disclose components for use in manufacturing articles such as printed circuit boards. The components are constructed of at least one sheet of copper foil that, when fabricated into a printed circuit board, constitutes a functional element of the board, i.e., the conductive paths. The other element of the component is a substrate sheet of aluminum that constitutes a discardable element of a finished printed circuit board. One surface of each of the copper sheet and the aluminum sheet is essentially uncontaminated and is engageable with the other surface at an interface.
A band of flexible adhesive joins the uncontaminated surfaces of the sheets together at their borders and defines a substantially uncontaminated central zone interiorally of the edges of the sheets and unjoined at the interface. The aluminum substrate provides stiffening for the copper foil and makes handling much easier.
The component may be constructed of two sheets of copper foil that in a finished printed circuit board both constitute functional elements of separate boards and a single sheet of aluminum that constitutes a discardable element. The inner surface of each of the copper sheets and both surfaces of the aluminum sheets are essentially uncontaminated and engageable with each other at interfaces on opposite sides of the aluminum.
While components of the type heretofore described have found advantageous application in the manufacture of printed circuit boards, in some laminating processes, a reaction between the aluminum and copper occurs resulting in a staining and discoloration of the copper. It is postulated that the cause of the staining of the copper may be the result of galvanic corrosion or may be the result of an oxidation of the aluminum and a subsequent reaction with the copper. In any event, to some laminators, this staining of the copper renders the resultant laminate(s) unusable.
The present invention provides a CAC type component having an aluminum substrate sheet and a coating thereon to prevent staining and discoloration of the copper foil during a lamination process.
In accordance with the present invention, there is provided a component for use in manufacturing articles such as printed circuit boards. The component is comprised of a sheet of copper foil which, in a finished printed circuit board, constitutes a functional element and a substrate sheet of aluminum which constitutes a discardable element. The aluminum has a coating layer on a surface thereof. One surface of the copper sheet and the coating layer on the substrate aluminum sheet are essentially uncontaminated and engageable with each other at an interface. A flexible adhesive joins the uncontaminated surfaces of the sheets together at their borders and defines a substantially uncontaminated central zone inwardly of the edges of the sheets and unjoined at the interface.
It is an object of the present invention to provide a copper/aluminum/copper component that is less susceptible to copper staining and/or corrosion.
It is another object of the present invention to provide a copper/aluminum/copper component as described above having a coated aluminum support substrate to prevent the aforementioned staining and/or corrosion problem.
It is a further object of the present invention to provide a copper/aluminum/copper component as described above, wherein the coating on the aluminum preferably does not transfer, contaminate or remain on the copper when the aluminum support substrate is separated therefrom.
These and other objects will become apparent from the following description of a preferred embodiment taken together with the accompanying drawings and the appended claims.